Russian rescue workers have called off the search for survivors of Friday's suicide truck bombing at a military hospital near Chechnya. The official death toll has reached 50, including military personnel and hospital staff.

The search operation ended after rescue workers decided there was no hope of finding any more victims alive under the rubble of the military hospital in southern Russia.

The four-story building collapsed and caught fire after a truck rammed through the gate and exploded. It was the latest in a series of suicide attacks in recent months that have been blamed on Chechen rebels fighting for independence from Russia.

The latest bombing was a blow to Russian President Vladimir Putin and his efforts to demonstrate that life is returning to normal in the war-torn region.

It also appeared to disclose gaps in security measures at key military and government installations that have been the main targets of similar attacks in and near Chechnya.

More than 200 people have now been killed in suicide attacks in the past year.

Military officials have ordered round-the-clock security patrols at hospitals, oil installations and other key buildings throughout the region.